Pyridoxal-Phosphate (PLP)


Chemical structure pyrodoxal phosphate and its Schiff's Base conjugate with lysine	3D representation of PLP

Vitamin B₆ Dependence: Humans do not synthesize pyrodoxine (the precursor to pyrodoxal phosphate) and therefore require its intake as part of the diet. pyrodoxine is one of the (many) B types typically called vitamin B₆. You may read much more about this and issues regarding its synthesis and deficiencies here.
PLP is involved in many different type of reactions (see below). Generally it forms a Schiff's Base with the amine group of amino acid. It can then perform a transamination of amino acids, or a decarboxylation or a racemization of the α Carbon or even a dehydration of a serine residue.

SOME ENZYMES USING THIS COFACTOR
transaminase Transports an amine to another molecule that has a ketone, this is an essential reaction in the synthesis of all amino acids
alanine racemase assocition with PLP makes the α Caron somewhat acidic - as the H+ goes back on it does so without stereochemistry and the amino acid become a mixture of D and L. The D amino acid is important in bacterial cell wall biosynthesis
serine dehydratase Removes the terminal hydroxyl group from serine and makes a double bond at the end in a typical elimination reaction.